Apple's purchase of Emotient fuels artificial intelligence boom in Silicon Valley

The arms race in Silicon Valley is on for artificial intelligence. Facebook is working on a virtual personal assistant that can read people's faces and decide whether or not to let them in your home. Google is investing in the technology to power self-driving cars, identify people on its photo service and build a better messaging app. Now Apple is adding to its artificial intelligence arsenal. The iPhone maker purchased Emotient, a San Diego maker of facial expression recognition software that can detect emotions to assist advertisers, retailers, doctors and many other professions.